Silver

Silver, a metallic chemical element. Like gold and platinum, silver is a precious metal because of its beauty and scarcity. Silver is harder than gold but not as hard as copper. Of all the metals, pure silver is the best conductor of heat and electricity. It is ductile (can be drawn into wire), malleable (can be hammered or rolled into a thin sheet), and an excellent reflector of light.

Silver is one of the most corrosion-resistant metals. It resists attacks by alkalies and all acids except nitric acid and hot concentrated sulfuric acid. Silver is not easily oxidized by air, and is insoluble in water. Because of its softness, silver must be alloyed with other metals for uses that subject it to wear.

Silver for centuries has been used in the arts and for coinage. Silver smithing, the art of producing decorative silver objects, was highly developed in Egypt by the 16th century B.C. Jewelry, tableware, vases, religious articles, and many other items are made of pure silver or alloys containing a high percentage of silver. The most important use of silver compounds is for the light-sensitive materials used in photographic films and papers.

The use of silver for coinage has virtually disappeared because of its high price. In the United States, silver was eliminated from dimes and quarters in 1965 and from half dollars in 1971. Silver certificates, last issued in 1963, were paper bills redeemable in silver until 1968. In 1986, a silver dollar weighing one troy ounce (31.1 g) was issued for collectors and investors. The coin's metal value is much higher than its face value, so it does not circulate.

Silver tarnishes on contact with sulfur or most sulfides. Unprotected silver will tarnish in air because of hydrogen sulfide gas, which comes mainly from the combustion of coal or oil in furnaces. To help prevent tarnish, silver objects may be stored in specially treated paper or felt, or in airtight containers. Display pieces are often coated with clear lacquer or silicone. Tarnish may be removed either by a fine abrasive polish or by various chemical processes.

Pure silver is called fine silver. The proportion of silver in jewelry, coins, and bullion is usually expressed in terms of fineness (the number of parts of silver in 1,000 parts of alloy). Example: an alloy that is 95 per cent silver is said to be 950 fine.

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